1. Field of the Invention
This invention relates to the protection of organic materials, such as rubber, plastic, lubricating oils, petroleum fuels, waxes, organic liquids, and the like, from oxidation by the use of antioxidants that are hydrazides and derivatives thereof
In a preferred embodiment, the present invention is directed to lubricants, especially lubricating oils. More particularly, the invention relates to a class of dispersant additives having antioxidant and viscosity index improving credit that are preferably derived from an ethylene-propylene diene modified terpolymer (EPDM) or an ethylene-propylene copolymer and a hydrazide or hydrazide derivative.
2. Description of Related Art
Organic materials such as rubber, plastic, lubricating oils, petroleum fuels, waxes, and organic liquids are well known to need protection from oxidation.
Currently, many of these organic materials are being exposed to higher operating temperatures and mechanical shear. New stabilizers that can protect organic materials from premature oxidation and degradation under these advanced operating conditions are being sought.
Further, in developing lubricating oils, there have been many attempts to provide additives that provide a lubricating oil with dispersancy of sludge and soot as well as high temperature deposit control. In addition, the formulation of an oil to meet high and low temperature viscosity requirements is critical and, in most cases, a viscosity index improver is employed to achieve this goal. Most multifunctional additives of the prior art provide one or two of these features.
It is well-known that internal combustion engines operate under a wide range of temperatures, including low temperature stop-and-go driving service, as well as high-temperature conditions produced by continuous high speed driving. Stop-and-go driving, particularly under cold, damp weather conditions, leads to the formation of sludge in the crankcase and in the oil passages of a gasoline or a diesel engine. This sludge seriously limits the ability of the crankcase engine oil to lubricate the engine effectively. In addition, the sludge, with its entrapped water, tends to contribute to rust formation in the engine. These problems can be aggravated by engine manufacturers' lubrication service recommendations, which typically specify extended oil drain intervals.
The polymers utilized in this invention can be obtained by a variety of methods known in the art. Such art can be represented by, but is not limited to, the following.
U.S. Pat. No. 3,928,497 discloses a process for preparing a graft-modified ethylene polymer or copolymer with a dicarboxylic acid graft-copolymerizable therewith or its graft-copolymerizable derivative in an alkyl-substituted aromatic hydrocarbon solvent in the presence of a radical initiator, characterized in that the reaction is performed while adding the dicarboxylic acid or its derivative gradually to the solvent in which the starting ethylene polymer or copolymer is present.
U.S. Pat. No. 4,517,104 discloses oil soluble viscosity index improving ethylene copolymers, such as copolymers of ethylene and propylene; and ethylene, propylene and diolefin; etc., that are reacted or grafted with ethylenically unsaturated carboxylic acid moieties, preferably maleic anhydride moieties, and reacted with polyamines having two or more primary amine groups and a carboxylic acid component, preferably alkylene polyamine and alkenyl succinic anhydride, such as polyisobutenyl succinic anhydride. Or the grafted ethylene copolymer can be reacted with already formed salts, amides, imides, etc. of the polyamine and acid component, preferably imides of alkylene polyamine and alkenyl succinic anhydride. It is said that these reactions can permit the incorporation of varnish inhibition and dispersancy into the ethylene copolymer while inhibiting cross-linking with resulting viscosity increase, haze or gelling. The grafting reaction may be carried out thermally, or more preferably with a free radical initiator, such as a peroxide in a mineral lubricating oil, in which case the acid component, preferably also acts to solubilize insoluble compounds formed by side reactions, such as maleic anhydride grafted oil molecules reacted with amine, to thereby inhibit haze formation, particularly when preparing oil concentrates of the V.I.-dispersant additive for later addition to lubricating oils. Preferred methods of grafting maleic anhydride onto the ethylene copolymer by periodic or continuous addition of maleic anhydride and initiator charge, so as to maintain the maleic anhydride in solution during the grafting reaction are also disclosed.
U.S. Pat. No. 4,693,838 discloses the reaction of hydrocarbon polymers, such as ethylene copolymers, with unsaturated nitrogen-containing monomers or unsaturated carboxylic acids in a synthetic hydrocarbon lubricating oil in the presence of a free radical initiator, such as a peroxide. The copolymer grafted directly with the nitrogen-containing monomers may be utilized as an additive for oil compositions, particularly lubricating oil compositions as a V.I.-dispersant additive. The polymer reacted with carboxylic acid may be further reacted with amines or amino-alcohols to also form a multifunctional V.I.-dispersant additive.
U.S. Pat. No. 4,340,689 discloses a process for grafting functional organic groups onto EPM and EPDM polymers wherein the grafting reaction is carried out in the cement in which the polymer is originally formed by solution polymerization.
U.S. Pat. No. 6,162,768 discloses dispersants and dispersant viscosity index improvers which include polymers of conjugated dienes which have been hydrogenated, functionalized, optionally modified and post treated. The dispersant substances include a copolymer of two different conjugated dienes. The polymers are selectively hydrogenated to produce polymers which have highly controlled amounts of unsaturation, permitting highly selective functionalization. The polymers may be functionalized by grafting of heteroatom-containing olefins. Also provided are lubricant fluids, such as mineral and synthetic oils, which have been modified in their dispersancy and/or viscometric properties by means of the dispersant substances. Also provided are methods of modifying the dispersancy and/or viscometric properties of lubricating fluids such as mineral and synthetic lubricating oils. The dispersant substances may also include a carrier fluid to provide dispersant concentrates.
U.S. Pat. No. 6,677,282 discloses hydrocarbyl substituted carboxylic compositions and derivatives thereof that are said to be useful as dispersant/viscosity improvers for lubricating oil and fuel compositions. Carboxylic compositions are derived from (A) a hydrocarbon polymer having Mn ranging from about 20,000 to about 500,000, and (B) an α,β-unsaturated carboxylic compound prepared by reacting (1) an active methylene compound of a formula (I), and (2) a carbonyl compound of a general formula (II), and lower alkyl acetals, ketals, hemiacetals and hemiketals of the carbonyl compound (2). Carboxylic derivative compositions are obtained by reacting the carboxylic compositions with a reactant selected from the group consisting of (a) amines characterized by the presence within their structure of at least one condensable H—N<group, (b) alcohols, (c) reactive metal or reactive metal compounds, and (d) a combination of two or more of any of (a) through (c), the components of (d) being reacted with the carboxylic composition simultaneously or sequentially, in any order.
U.S. patent application Publication No. 2003/0030033 discloses a composition comprising an N-aromatic substituted acid amide compound selected from the group consisting of compounds of a specified formula (I). These compositions may be used as such or they may be bound to a polymer backbone via a linking moiety. In either case, they are useful as antioxidants, particularly in lubricating oil compositions.
WO 03/025034 discloses a process that comprises solution grafting a hydrocarbon polymer prepared from at least one C2 to C28 polymerizable hydrocarbon, said polymer having a number average molecular weight in the range of from about 5,000 to about 500,000 with an ethylenically unsaturated C3 to C10 carboxylic acid material, using a free radical initiator in the presence of a structurally defined ester oil.
Metal deactivators for polyolefins based on hydrazides are also known in the art, e.g., Copper Deactivators For Polvolefin Insulation, Chan, M. G. et al., Bell Lab., Murray Hill, N.J., USA. Proceedings of International Wire and Cable Symposium 27:99-106 (1978); and U.S. Pat. No. 4,100,132, which discloses certain imido-oxamide-type compounds and derivatives thereof which are useful for preventing metal catalyzed oxidative degradation of polyolefins. The specification also relates to olefin homopolymer and copolymer compositions containing such compounds and derivatives thereof and to a method for enhancing the resistance of olefin homopolymers and copolymers against metal-catalyzed oxidative degradation by incorporating these compounds therein.
These references describe imido-oxamide-type compounds and derivatives thereof, which are useful for preventing metal catalyzed oxidative degradation of polyolefins. The disclosed structure is below:
wherein Z is a bivalent radical which together with the dicarboximide group forms a monocyclic or polycyclic ring system and is selected from the group consisting of phenylene, cyclohexylene, cyclohexenylene, cyclohexenylene substituted by a methyl group, norbornenylene, ethylene, vinylene and tetradecenylene.
These compounds are effective in deactivating metals in plastic materials, but are limited by two factors: (1) they do not exhibit any primary antioxidant performance on their own, and (2) they are substantially insoluble in oil.
It is an object of the present invention to address both of these issues around hydrazide metal deactivators, either by providing metal deactivation (MD) activity as an oil soluble additive or MD/antioxidant activity as an oil soluble additive. Another objective is to provide hydrazide monomers that provide antioxidant performance.
The disclosures of the foregoing are incorporated herein by reference in their entirety.